Block-signal system.



L. A. HAWKINS.

BLOCK SIGNAL SYSTEM. APPLICATION FILED JAN. 31 1910.

Patented Dec. 8, 1914.

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257.5 ATTUHNE'X JN LAURENCE A Ha YWCNS. BY'

WITNESSES: W ,m, ZZZ; M

UNITED STATES OFFICE.

LAURENCE A. HAWKINS, OF SCHENECTADY, NEW YORK, ASSIGNOR, BY MESNE ASSIGNMENTS, TO THE UNION SWITCH AND SIGNAL COMPANY, A CORPORA- TION OF PENNSYLVANIA.

BLOCK-SI GNAL SYSTEM.

Specification of Letters Patent.

Patented Dec. 8, 1914.

To all whom it may concern:

Be it known that I. LAURENCE AJIiAw- Kiss, a citizen of the United States, residing at Schenectady, county of Schenectady, State of ew York. have invented certain new and useful Improvements in Block- Signal Systems, of which the following is a specification.

My invention relates to block signal systems for electric roads and consists in an improvement in the arrangement of track circuits and rail connections disclosed in my prior Patent No. 929,591, dated July 27. 1909.

In my prior patent I disclosed a system of rail connections for electric railways employing the track rails as return conductor for the power current and having a plurality of parallel tracks in which one rail of each track was bonded throughout its length, so as to be conductively continuous for all currents. and the other rail sectioned to form the signal blocks, while alternate rail sections of one track were connected at both ends to the adjacent rail sections of another track so as to form a third continuous conductor for the power current independent of the two continuous rails. Thus, if a road has two tracks, threefourths of the total rail conductivity is employed for returning the power current, while if a. greater number of tracks are used the proportion of total rail conductivity employed may he still greater.

The object of my present invention is so to arrange the track circuits that the tracks may be cross-lmnded every block, and to arrange the cross-bonds in such a way that they will not interfere with the proper operation of the signal circuits.

In the system of my prior patent I disclosed one arrangement in which those blocks, the sectional rails of which were connected to other blocks, have their sources of current or track transformers connected to their centers. Now if adjacent blocks of the 'same track having their sources 0 current connected to their centers have those sources relatively oppositely connected, points of zero'potential will be produced approximately half way between those sources and between the continuous rail of the track to which those blocks belong and the sectional rail of the other track. Between these points a cross-bond may he placed without a lfecting the operation of the system. With frequent cross-bonding. however, current may (low from one track to the other, and in order to prevent the cur rent from one track ati'ecting the relays of the other track, my invention. in another aspect further consists in using currents of dilferent characters for ditlerent tracks. Thus, the current supplied to the track circuits of one track may be of one phase and the currents supplied to the track circuits of the other track may be of another phase such that it will not affect the relays of the tirst track. My invention in this latter aspoet is not limited to the track circuit ar,- 7O

rangement of my prior patent, but is applicahle to an railway, having any track circuit arrangement, in which there are a plurality of tracks. the rails of which form a plurality of return conductors for the power current. and in which frequent crosshonding between tracks is desirable.

In the appended claims I have pointed out specifically what I consider to be the novel features of my invention, which will best he understood by reference to the accompanying drawing which shows diagrammatically a block signal system arranged in accordance with my invention.

In the drawing, A and A represent respectively the rails of two tracks of a double track electric railway. The upper rail A and the lower rail A are both bonded througl'iout in the usual manner so as to be conductively continuous for all currents. Alternate sections of the sectionalized rail of each track are connected at both ends to the adjacent ends of adjacent rail sections of the other track. In this manner a third continuous conductor is formed for the return of the power current independently of the continuous rails. The connections between the rail sections forming this third continuous conductor are represented at a a.

B to B inclusive represent the signals TO] the blocks. of which six are shown ii. he drawing. three for each track.

C represents a generator supplying current for the signal circuits. I have repre sented a two-phase generator and a threewire transmission system, 0, c, c, the wire 0 being common to both phases. The purpose of a poly-phase transmission circuit is to furnish currents of different phases to the track circuits of the two tracks.

D, D and 1) represent transformers for supplying current to the track circuits of the track A. These transformers all have their primaries connected between the transmission wires 0 and 0 The transformers D and D which are connected to blocks having their sectional rails connected to sectional rails of the other track, are connected to thecenters of their blocks, while the transformer D is connected to the outgoing end of its block.

E to E represent track relays. These are shown diagrammatically as of the wel1- known induction type each comprising a short-circuited secondary member 6 carrying the relay contacts, a winding 6 connected to the track rails, and a second winding 0' supplied with current independently of the track circuits from transformers F to F, certain of which transformers also serve to supply current for actuating the operating mechanisms of the signals. In the blocks having the track transformers connected to their centers, as. for instance, in

the block to which the signal B belongs, two

track relays E and E, are employed, one at each end of the block. The purpose of the central connection of the transformer with relays at each.end of the block is to place the relays nearer to the transformer which supplies them than to other transformers which could possibly supply current to them. The relay E for instance, is distant only one-half a block from transformer D, while it is distant a block and a half from transformer D Since the block to which signal B belongs has one rail completely insulated from the other track circuits. the central connection of the transformer is not necessary. so that I have indicated transformer D at one end of the block and a single relay E at the other end. A noninductive resistance (Z is placed in series with the secondary of each track transformer and similar resistances (l are in series with the track windings of the relays. These resistances are to prevent the cores of transformers or relays from being saturated by the power current. due to an unbalancing of the power current in the rails. and also have the etl'ect. so far as the transformers are concerned. of preventing a train when short-circuiting a transformer for drawing excessive current from it. Resistanccs (l are placed in series with relay windings r so as to give to the circuits of these windings the same power factor as that of the track circuits. These windings of relays F. E,, C, E and i, are supplied from the other phase than that to which track transfer-net's D. D and D are connected. Thus the currents in the two windings of these relays are 90 degrees out of phase, thus iving maximum torque.

'The transformers D and D each have one terminal connected to the continuous rail of the track A and the other terminal connected to alternate sections of the sectionalized rail of this track; these sections are connected together through rail sections of the other track. If these transformers are relatively oppositely connected, as is shown for their primaries, a point of zero potential will exist approximately midway betwecn them. These points are approximately at the center of the intervening block between the continuous rail A and the sectionalized rail A. These two points can, therefore, be connected together by a cross-bond 0' without interfering with the operation of the signal circuits. Since the presence of this bond insures the maintenance of Zcropotential between its ends. it is not absolutely essential that transformers D and D should be relatively oppositely connected. but the relatively opposite connection is preferable. since. when it is used, a breaking of the bond 0. can have no effect on the operation of the circuits. whereas, if transformers D and D were similarly connected and the bond (1 were broken. current from transformer I) would tend to energize relay E and current from transformer D would tend to energize relay P1,.

lVith the frequent cross-bonding em ployed, current from one track may flow into the other track and in case of broken rails this straying current may reach a considerable amount. For instance. suppose the upper rail A were broken between transformer D and relay E: current might then flow from the right-hand secondary terminal of transformer D. through resistance (I, cross-bond 1 upper rail resistance J and winding c of relay E bond 0, winding 1" and resistance 11 of relay E, and lower rail back to the lefthand terminal of transformer D. The transformer would under these conditions be delivering the same amount of currentto relays E and E and if this current could affect relay I? a dangerous condition might result. In order to prevent current from one track affecting the relays of the other track. trans- ,formers D. D and D". which supply the track circuits of track are connected to a ditl'ercnt phase of the transmis ion circuit than that to which the transformers D, D and D are connected. The latter trans formers are conncctml to wires c and r. while the former are connected across wires 1* and c. The difference in phase between the currents impressed on the two tracks is thus 90 degrees. Now since the current in the windings c of the relays of track .& is ninety degrees out of phase with the track the windings e of the relays of t-rack'A- carry currents 90 degrees out of phase with the track currents of track A and in phase with the track currents of track A, which latter currents cannot. therefore. affect these relays.

Many modifications may be made in the arrangement shown withoutdeparting from the spirit of niy invention. For instance, in place of using resistances a for obtaining the proper phase of the currents in the relay windings 6 any other suitable arrangement-of connections may be employed for giving the desired phase difierence of 90 degrees in the two windings of'each relay. Furthermore, while I have selected a phase difference as the difference of character in the track currents of the two tracks for the purpose of preventing interference, it is obvious that other differences of character may be employed provided they prevent interference. Accordingly, I donotgiesire to limit myself to the particular connections and arrangement of parts shown and described, but aim in the appended claims to cover. all modifications which are within the scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is;-

1. In an electric,railway employing the track rails as return conductor for the power current, a plurality of parallel tracks each having onerail conductively continuous for all currents and the other sectioned to form signal blocks, bonds conductive for all cur rents connecting alternate rail sections of one track in series with alternate rail sections of another track thus forming a continuous conductor for power current inclependent of the continuous rails, and crossbonds between tracks each extending from a point near the center of, a rail section which is included in said continuous conductor to an approximately opposite point on the continuous rail of the other track.

2. In an electric railway employing the track rails'as return conductor for the power current, a plurality of parallel tracks each having one-rail conductively continuous for all currents and the other sectioned to form signal blocks, bonds conductive for all currents connecting alternate rail sections of one track in series with alternate rail sections of another track thus forming a continuous conductor for power currentindependent of the continuous rails, cross-bonds between tracks each extending from a point near the center of a rail section which is included in said continuous conductor to an approximately-opposite point on the continuous rail of the other track, sources of current connected to the railsof the'several blocks, those blocks, the sectional rails of which are included in said continuous conductor, having their sources connected 'to their centers, and signahcontrolling relays connected to the rails, the blocks having their sources connected to their centers havin; a relay at each end.

3. In an electric railway employing the track rails as return conductor for the power current, a plurality of parallel tracks each having one rail conductively continuous for all currents and the other sectioned to form signal blocks, bonds conductive for all currents connecting alternate rail sections of one track in series with alternate rail sections'of another track thus forming a continuous conductor for power current independent of the continuous rails, cross-bonds between tracks each extending from a point near the center of a rail section which is included in said continuous conductor to an approximately opposite point on the continuous rail of the other track, sources of current connected to the rails of the several blocks, those blocks, the sectional rails of which are included in said continuous conductor, having their sources connected to their centers, adjacent blocks of the same track which have, their sources connected to their centers having their said sources relatively oppositely connected, and signal-com trolling relays connected to the rails, the blocks having their sources connected to their centers having a relay at each end.

4. In an electric railway employing the track rails as return conductor for the power current, a plurality of parallel tracks each having one rail conductively continuousfor all currents and the other sectioned to form signal blocks, connections conductive for all currents between rail sections of different tracks forming with said sections a continuous conductor for power current independent of the continuous rails, signal-controlling relays connected to the. track rails, and sources of alternating current for said re lays connected to the track rails, the currents supplied to one track being of a different character from that supplied to air other track.

5. In an electric railway employing the track rails as return conductor for the power current, a plurality of parallel tracks each having one rail conductively continuous for all currents and the other sectioned to form signal blocks, the blocks of each track being substantially oppositely located, connections conductive for all currents between both ends of alternate rail sections of one track and the adjacent ends of the intermediate sections of another track, said con nections forming with said railv sections a continuous conductor for power current in- '3 dependent of the continuous rails, signalcontrolling relays connected to the track rails, and sourc s of alternating current for said relays conn cted to the track rails, the currents supplied to one track being of a different character from that supplied to another track.

6. In an electric railway employing the track rails as return conductor forthe power current, a plurality of parallel tracks having their rails connected to form a plurality of return conductors for the power current, cross-bonds cross-connecting the rails of different tracks every block, signalcontrolling relays connected to the track rails, and sources of alternating current for the relays connected to the track rails, the current supplied by the sources for different tracks being of different characters.

7. In an electric railway employing the track rails as return conductor for the power current, a plurality of parallel tracks each having one rail conductively continuone for all currents and the other sectioned to form signal blocks, bonds conductive for all currents connecting alternate rail sections of one track in series with alternate rail sections of another track thus forming a continuous conductor-for power current independent of the continuous rails, crossbonds between tracks each extending from a point near the center of a rail section which is included in said continuous conductor to anapproximately opposite point on the continuous rail of the other track, signal controlling relays connected to the track rails, and sources of alternating current for the relays connected to the track rails, the currents supplied by the 'sources for different tracks being of different characters. I

all currents connecting alternate rail sections of one track in series with alternate rail sections of another track thus forming a continuous conductor for power current independent of the continuous rails, crosssources of current connected to the rails r of the several blocks, those blocks, the sectional rails of which are included in said continuous conductor, having their sources connected to their centers, the current supplied by the sources for different tracks be ing of different characters, and signal-com trolling relays connected to the rails, the

blocks having their sources connected to their centers having a relay at each end.

9. In an electric railway the track rails of which are included in the circuit of the propulsion current, a plurality of parallel track's each having [one rail conductugely continuous for all currents and the other rail sectioned to form signal blocks, the blocks of each track being substantially oppositely located, connections conductive for all currents between" both ends of alternate rail sections of one track and the sections of another track adjacent the sections opposite said alternate sections, said connections forming with said rail sections a continuous conductor for power current independent of the continuous rails and cross bonds between v tracks each extending from a point near the center of a rail section which is included in said continuous conductor to an approximately opposite point of the continuous rail of the other track. a

In witness whereof, I have hereunto set my hand this 29th day ofJa-nuary, 1910.

LAURENCE A. HAWKINS.

itnesses BENJALIIN B. HULL, HELEN ORFoRD.

Copies of this patent may obtained for five cents each, by addressing the Commissioner of Patents.

' Washington, D. C." 

